Lubricant composition



United States Patent 3,245,908 LUBRICANT COMPOSITION Warren Lowe,Berkeley, Calif., assignor to Chevron Research Company, a corporation ofDelaware No Drawing. Filed Nov. 18, 1963, Ser. No. 324,177 3 Claims.(Cl. 25251.5)

This invention relates to novel lubricating compositions. Moreparticularly, it relates to lubricant comp0- sitions having superiornon-corrosive and non-deposit forming properties.

Lubricating oils, under normal operating conditions, generally undergooxidative deterioration resulting in the production of substances highlycorrosive to metal parts of modern engine and like machinery.Particularly susceptible to such corrosion are the alloy metal (usuallycopper-lead) bearings employed in todays internal combustion engines.

Therefore it is necessary to add to the lubricating oils, substanceswhich act to reduce the corrosive effect upon the metal surfaces.Corrosion inhibitors which have been employed in the past have not beencompletely satisfactory. A number of additives have been employed thatwere not highly effective, thus allowing corrosion of the parts soughtto be protected. Others, while quite effective initially, are used uprapidly in service and lose their effectiveness.

Another problem of many prior art anticorrodents has been the fact thatthey could not be combined successfully in compositions with additivescommonly used to eifect wear inhibition, sludge inhibitors, pour pointdepression, detergency, etc. Thus, a desirable inhibitor may be combinedwith these types of additives without adversely affecting the propertiesof either the anticorrodent or the other additive.

Furthermore, many known corrosion inhibitors contain active sulfur andare thus undesirable for use with bearings containing silver and similarmetals. The use of silver-containing bearings has greatly increased insuch classes of engines as marine and locomotive diesels. Thus,non-sulfur-containing lubricants possessing anticorrodent properties areespecially desirable.

The use of phthalic acids, especially isophthalic and terephthalic acidsas corrosion inhibiting components of lubricant compositions isdescribed in Stewart et al. US. Patent 2,809,160. These compoundsrepresent highly effective corrosion inhibitors possessing manydesirable characteristics such as the ability to be used in combinationwith numerous classes of both lubricating oil bases and lubricantadditives of various types. However, in some applications, when thesecompounds are combined in lubricating compositions with certainnitrogen-containing detergents, while excellent anticorrodent propertiesare displayed, a decrease in detergent activity often results. Thustheir use results in an increase in the amount of varnish and othercarbonaceous deposits deposited upon piston valves and skirts and inpiston ring grooves. These deposits are deleterious to engine operationand their elimination is a highly desirable objective evidenced bynumerous advances recently made in producing better detergent typeadditives.

It has now been found that a new and superior lubrieating compositionhaving excellent non-corrosive and non-deposit forming characteristicscan be prepared from a major proportion of an oil of lubricatingviscosity in combination with a high molecular weightnitrogen-containing detergent type additive, said combination beingcorrosive to metal surfaces in normal use, and a minor portionsufiicient to inhibit corrosion of 2,2'-biphenyl dicarboxylic acid.

The novel lubricating compositions of this invention are characterizedby remarkable corrosion inhibiting properties over extended operationalperiods and by greatly improved lubricating of bearings and othersliding surfaces. An outstanding advantage of the particular inhibitorlies in the fact that its addition results in no increase in thedeposit-forrning characteristics of the compositions, a result commonwith the inhibitors of the prior art. As noted above, of particularadvantage is the ability of these compositions to provide superiorlubrication for particular bearings such as silver-containing bearingsWithout the usually concommitant tendency to form underhead deposits insuch heavy duty diesel service.

The corrosion inhibiting characteristics of 2,2'-biphenyldicarboxylicacid are obtained in particular in combination with recently developednitrogen-containing nonmetallic ashless detergents in lubricating oilcompositions. Examples of such detergents are those derived from alkenylsuccinic anhydrides having 30 or more carbon atoms in the alkenyl groupand amine compounds, such as tetraethylene pentarnine, N-aminoethylpiperazine, dimethylaminopropylamine, etc.

The detergent additive is obtained by heating an alkenyl succinicanhydride with at least 0.5 mole of an amine.

The substituted succinic anhydrides contemplated as reactants in theprocess can be readily obtained by heating maleic anhydride with a highmolecular weight olefin or with a chlorinated high molecular weightolefin at a temperature from about to 200 C. Typical high molecularweight olefins which can be employed are polyethylene, polypropylene,polyisobutylene, etc. Polyisobutylene is preferred.

Examples of suitable polyamine reactants are ethylenediamine, diethylenetriamine, tetraethylene pentamine, and the like. Tetraethylene pentamineis a preferred polyamine reactant.

A preferred embodiment of the detergent additive is the product obtainedby heating one mole of a polyisobutenyl succinic anhydride having about65 carbon atoms in the olefin chain with 0.9 mole of tetraethylenepentamine.

The detergent additive is employed in the lubricant composition in anamount suflicient to impart detergency. Generally, amounts from 0.1 to10% by weight are preferred.

The additives are a class of chemical compounds recognized in the art aspossessing the ability to enable a lubricating oil medium to maintainoxidation products, resins, and other insoluble material in suspensionor disprobably due to the removal of naturally formed protective filmsfrom bearings and other sliding surfaces. Thus the use of a compatibleand efficient corrosion inhibitor with these types of compounds isespecially desirable.

The corrosion inhibitor of this invention is employed in an amountsulficient to inhibit corrosion. In general, amounts up to about 1.0% byWeight are suflicient. A preferred range for most lubricant compositionsis from about 0.01% to about 0.5% by weight.

Any of the Well-known types of lubricating oils can be used as the baseoils for the compositions of this invention. These oils are corrosive tometal surfaces under normal operating conditions. Examples of such baseoils are naphthenic base, parafiin base, and mixed base mineral oils;synthetic oils, for example, alkylene polymers, such as polymers ofpropylene, butylene, etc., and mixtures thereof; alkylene oxide typepolymers; dicarboxylic acid esters; phosphorous esters; silicon esterssuch as si1icates and polysiloxanes; and alkyl aromatic hydrocarbons.

As previously mentioned, the corrosion inhibitor of EXAMPLE I 0.15% byweight of 2,2'-biphenyldicarboxylic acid was added to a lubricatingcomposition comprising 3.0% by weight of a polybutenyl succinimidedetergent type additive in a lubricating oil base which was a solventrefined paraffinic neutral oil of SAE 30 grade. The detergent wasprepared by heating 1 mole of polybutenyl succinic anhydride havingabout 65 carbon atoms in the alkenyl chain with 0.9 mole oftetraethylene pentamine.

In order to demonstrate the effectiveness of 2,2'-biphenyldicarboxylicacid as a non-deposit forming anticorrodent, the lubricant compositionprepared in Example I was subjected to the L-4 Engine Test and comparedwith a simple of base oil containing the same detergent and with asample containing 0.15% by weight of terephthalic acid as a corrosioninhibitor.

In the L-4 test, the corrosion characteristics of a lubricantcomposition is determined in a Chevrolet standard 6-cy1inder engine.Weighed copper-lead test bearings and new piston rings are installed.The test is run at a constant engine speed at about 3000 rpm. under aload of 30 brake horsepower for a period of 36 hours after a runinperiod of 8 hours. The outlet temperature of the jacket coolant is about200 F. and the oil sump temperature about 280 F. At the conclusion ofthe test the engine is disassembled and the pistons are removed andinspected for varnish deposits and rated for cleanliness on a basis ofto 10, 10 being perfectly clean. The bearings are weighed to determinetotal weight loss due to corrosion. Table I describes the results oftests performed comparing the additive of this invention withterephthalic acid.

Table I As shown by the above data, 2,2'biphenyldicarboxylic acidcompares favorably with terephthalic acid in its ability to reducebearing corrosion with this type of lubricant composition. However, itsgreat superiority lies in the fact that it does not contribute tolowering the varnish rating of the engine as does the terephthalic acid.Thus 2,2-biphenyldicarboxylic acid provides excellent corrosioninhibition under actual engine operation and aids in maintainingextremely high engine cleanliness ratings.

The L4 Engine Test is more iully described in the CRC Handbook, 1946edition, Coordinating Research Council, New York, New York.

I claim:

1. A lubricant composition comprising a major portion of an oil oflubricating viscosity in combination with a minor portion of an alkenylsuccinimide lubricating oil detergent sufficient to impart detergency,said combination being corrosive to metal surfaces in normal use and aminor portion sufficient to inhibit corrosion, of2,2biphenyldicarboxyiic acid.

2. The lubricant composition of claim 1 wherein the oil of lubricatingviscosity is a mineral lubricating oil.

3. The lubricant composition of claim 1 wherein the detergent additiveis a polybutenyl succinimide prepared from a polybutenyl succinicanhydride having about carbon atoms in the alkenyl chain andtetraalkylene pentamine, said detergent additive being present in anamount of from 0.1% to 10% by weight.

References Cited by the Examiner DANIEL E. WYMAN, Primary Examiner.

P. P. GARVIN, Examiner,

1. A LUBRICANT COMPOSITION COMPRISING A MAJOR PORTION OF AN OILLUBRICATING VISCOSITY IN COMBINATION WITH A MINOR PORTION OF AN ALKENYLSUCCINIMIDE LUBRICATING OIL DETERGENT SUFFICIENT TO IMPART DETERGENCY,SAID COMBINATION BEING CORROSIVE TO METAL SURFACES IN NORMAL USE AND AMINOR PORTION SUFFICIENT TO INHIBIT CORROSION, OF2,2''BIPHENYLDICARBOXYLIC ACID.